It is well known that certain particles can be used to add performance properties to materials in different forms such as gases, liquids, and solids. These particles can have properties that are suitable for odor adsorption, moisture management, ultraviolet light protection, chemical protection, bio-hazard protection, fire retardance, antibacterial protection, antiviral protection, antifungal protection, antimicrobial protection, and other factors, and combinations thereof.
These particles can provide such properties because they are “active”. Active particles are active because they have the capacity to adsorb or trap substances, including substances that may themselves be a solid, liquid, and/or gas, for example, pollen, water, butane, and ambient air. Active particles have an adsorptive property because each particle has a multitude of pores (e.g., pores on the order of thousands, tens of thousand, or hundreds of thousands per particle). It is these pores that provide the active particle with its capacity to adsorb. For example, an active particle such as activated carbon can adsorb a substance (e.g., butane) by trapping the substance in the pores of the activated carbon.
Exposing the active particles to a substance can prematurely deactivate the active particles by blocking or inhibiting the pores, thus reducing the adsorptive capacity of the active particles. That is, once the pores are blocked or inhibited with a substance, those blocked or inhibited pores may be prevented from further adsorption. However, the adsorptive capacity of active particles can be increased or restored by removing the substance that is blocking or inhibiting the pores. Hence, active particles can be rejuvenated (e.g., reactivated).
A common problem often associated with active particles is that they can be prematurely deactivated. When active particles are premature deactivated, the particles cannot adsorb substances originally intended to be adsorbed, but instead, adsorbed some undesired substance. Some substances that are prematurely adsorbed may be deleterious substances. Deleterious substances are substances that cannot be easily removed from an active particle and therefore reduce the active particle's capacity for further adsorption. For example, a deleterious substance such as a molten polymer may permanently deactivate active particle. A molten polymer, for example, cannot be removed without damaging the active particle or the substance surrounding the active particle.
Other substances that are prematurely adsorbed may be relatively easy to remove. That is, these types of substances can be removed using known methods of rejuvenation or reactivation that do not damage the active particles or the surrounding substance. For example, when a non-deleterious substance such as methane is adsorbed, it may be removed from the active particle by heating the particle.
Advances in producing materials with active particles contained therein have been limited by adverse conditions encountered when making such materials. One such process includes, for example, an extrusion process that is used to produce strands of synthetic yarn. In an extrusion process, the process typically begins by converting a base material, such as a polymer, into a molten mixture. Then, using the molten mixture, a desired material (e.g., yarn) is extruded through an extrusion apparatus. However, when the active particle is mixed into a molten mixture, the molten mixture can deactivate the active particle by filling the particle's pores, thus inhibiting the active particle's ability to adsorb.
Various extrusion approaches have been attempted to prevent active particle deactivation, but all have produced results that are ineffective or substantially weaken the base material. One approach, using activated carbon, has yielded a material having about 4% of the activated carbon by weight embedded therein as active. However, this approach required a heavy loading of activated carbon in order to produce a yarn that has at best only 4% activity out of all the carbon embedded within the yarn. A drawback of having to heavily load yarn with activated carbon or other active particle is that it results in a yarn that possesses the physical characteristics of the activated carbon (or particle) rather than the physical characteristics of the base material used to produce the yarn. Thus, a yarn or fabric created using this method has a hand and feel dominated by the carbon (or particle) additive and not the base material. Moreover, as the carbon (or particle) loading increases, the tensile strength of the base material decreases, resulting in a brittle, and non-stretching fabric.
In view of the foregoing, it is an object of the invention to preserve active particles with a removable protective substance.
It is also object of the invention to remove the removable protective substance to rejuvenate or reactivate the active particles, when desirable.
It is another object of the invention to provide an active particle that is deactivated with a removable encapsulant for protection against premature deactivation.